Field
Apparatuses and methods consistent with exemplary embodiments relate to an optical disc and an optical disc reproduction apparatus for reproducing the same, and more particularly, to an optical disc which stores various information to be efficiently reproduced, and an optical disc reproduction apparatus for reproducing the same.
Description of Related Art
Generally, an optical disc reproduction apparatus reproduces data recorded on a disc such as compact disc (CD), compact disc-read only memory (CD-ROM), digital versatile disc (DVD), blu-ray disc (BD), CD-R, CD-RW, DVD±RW, or DVD-R.
The trend is moving forward to higher definition image content, and optical discs need to be able to store high-capacity data in order to store high-definition images. One way to store high-capacity data on an optical disc is to record data on only one layer; however, recent optical discs have a plurality of layers, each generated to record data thereon.
For an optical disc having a plurality of layers, more delicate and accurate techniques are necessary for inter-layer transition and for control or automatic adjustment of the respective layers. Particularly, optical discs having a high density of layers exhibit great differences in the servo signals on the respective layers at a stationery collimator lens (CL). Related technologies suffer the following shortcomings because they use an average value of several optical discs, and do not have specific information on the respective layers.
First, during a pull-in operation, the lack of information on the respective layers causes a deterioration of the stability of the servo signals detected by the optical disc reproduction apparatus when the position of the CL is misaligned, and in some cases, the focus-on operation sometimes fails when the size of a focus error signal (or focus drive signal) is too big or too small.
Further, during inter-layer transition, inter-layer transitions by way of layer jump are difficult in the beginning, even during stable operation on the current layer, due to a lack of information about the next layer. In the worst case, the inter-layer jump is ON on a layer different from n intended layer, or the layer jump itself fails.
Further, even when the focus is ON on the intended layer, the position of the CL or gain value by the amount of reflection may not be correct, in which case the initial value for automatic adjustment is deviated from the actual optimum value, requiring more steps for the transition in the automatic adjustment. As a result, servo drop occurs, or time is delayed during automatic adjustment. An optical disc which is considerably different from an initial value for the automatic adjustment can even cause a disc misjudgment.
Additionally, related art optical discs do not provide information about data transfer rate, or even if they do have information about data transfer rate, such information is limited to the overall basic transfer rate. Accordingly, an optical disc reproduction apparatus drives a driver at a spindle speed which corresponds to maximum velocity. If the apparatus fails to drive the driver at the spindle speed which is the maximum velocity supported, the transfer rate of the data read by the optical disc reproduction apparatus at a certain time point of increasing the transfer rate does not achieve the transfer rate as required by the optical disc. When this phenomenon continues for a predetermined time, a buffer underrun occurs. As a result, a data gap occurs for a predetermined time, which causes problems such as the image or sound being stopped.
In order to deal with the problems mentioned above, related art solutions set the spindle speed to the maximum velocity. This means that the data transfer rate is faster than the transfer rate required by the optical disc, and accordingly, a phenomenon such as buffer underrun does not occur. However, as the driver has to be kept driving at the high-velocity spindle speed, noise and vibration are generated. Additionally, current consumption also greatly increases.